This invention relates to a weighing device, particularly to a hydraulic bellow type scale.
The simplest form of weighing device is the equal-armed beam scale. It consists of a beam pivotally mounted on a knife-edge fulcrum at the center. Attached to the center of the beam is a pointer which points vertically downwards when the scale is in equilibrium. The equal-armed scale requires a set of weights at least as heavy as heaviest load to be weighed. For the weighing of heavier objects, scales having arms of unequal length such as pendulum type weighing machine and letter balance are therefore used. Another type of scale is the spring balance. In this device the extension of the spring is proportional to the magnitude of the load suspended from it. The scale can be directly graduated in weight units. The familiar "bathroom scales" are also based on the spring balance principle. Since they are based on either lever balance or spring balance principle, the scales as set forth have relatively great error in measurement.